title: Repair kinetics of acrolein- and (E)-4-hydroxy-2-nonenal-derived DNA adducts in human colon cell extracts.
abstract: ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) play a role in the pathogenesis of colon cancer. Upon oxidation, PUFAs generate α,β-unsaturated aldehydes or enals, such as acrolein (Acr) and (E)-4-hydroxy-2-nonenal (HNE), which can form cyclic adducts of deoxyguanosine (Acr-dG and HNE-dG, respectively) in DNA. Both Acr-dG and HNE-dG adducts have been detected in human and animal tissues and are potentially mutagenic and carcinogenic. In vivo levels of Acr-dG in DNA are at least two orders of magnitude higher than those of HNE-dG. In addition to the facile reaction with Acr, the higher levels of Acr-dG than HNE-dG in vivo may be due to a lower rate of repair. Previous studies have shown that HNE-dG adducts are repaired by the NER pathway (Choudhury et al. [42]). We hypothesize that Acr-dG adducts are repaired at a slower rate than HNE-dG and that HNE-dG in DNA may influence the repair of Acr-dG. In this study, using a DNA repair synthesis assay and a LC-MS/MS method, we showed that Acr-dG in a plasmid DNA is repaired by NER proteins, but it is repaired at a much slower rate than HNE-dG in human colon cell extracts, and the slow repair of Acr-dG is likely due to poor recognition/excision of the lesions in DNA. Furthermore, using a plasmid DNA containing both adducts we found the repair of Acr-dG is significantly inhibited by HNE-dG, however, the repair of HNE-dG is not much affected by Acr-dG. This study demonstrates that the NER repair efficiencies of the two major structurally-related in vivo cyclic DNA adducts from lipid oxidation vary greatly. More importantly, the repair of Acr-dG can be significantly retarded by the presence of HNE-dG in DNA. Therefore, this study provides a mechanistic explanation for the higher levels of Acr-dG than HNE-dG observed in tissue DNA.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Choudhury
authors.forename: Marcin
authors.initials: M
authors.lastname: Dyba
authors.forename: Jishen
authors.initials: J
authors.lastname: Pan
authors.forename: Rabindra
authors.initials: R
authors.lastname: Roy
authors.forename: Fung-Lung
authors.initials: FL
authors.lastname: Chung
mesh_terms: D000171:Acrolein / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism*; D002457:Cell Extracts; D002474:Cell-Free System; D002478:Cells, Cultured; D003106:Colon / Q000166:cytology*; D018736:DNA Adducts / Q000378:metabolism*; D004260:DNA Repair; D006801:Humans; D007536:Isomerism; D007700:Kinetics; D053719:Tandem Mass Spectrometry
chemical_list: D000447:Aldehydes; D002457:Cell Extracts; D018736:DNA Adducts; D000171:Acrolein; C027576:4-hydroxy-2-nonenal
keywords: (E)-4-hydroxy-2-nonenal; 1,N(2)-Propano-dG; 4-Hydroxy-2-nonenal; ACN; Acr; Acrolein; BEH; BER; CE; DNA adduct; ESI; HNE; HNE-dG; HNE-derived 1,N(2)-deoxyguanosine adducts; HPLC; Human colon cells; LC; MRM; MS; MS/MS; NER; Nucleotide excision repair (NER); OHPdG (Acr-dG); P-dG; PUFA; Repair kinetics; UPLC; acetonitrile; acrolein; base excision repair; bridged ethyl hybrid; collision energy; electrospray ionization; high performance liquid chromatography; liquid chromatography; mass spectrometry; multiple reactions monitoring mode; nucleotide excision repair; polyunsaturated fatty acid; tandem mass spectrometry; ultra performance liquid chromatography.; α- and γ-OH-1,N(2)-propanodeoxyguanosine